Others might disagree but I would try a 3" thick maple butcher block under the speakers, and the speakers with spikes sitting on the butcher blocks. You could also try the set up I described above with three or four per butcher block (cork rubber cork) blocks under the butcher blocks.
As an example #1: https://www.audiogon.com/listings/lis997ac-sq-products-isol-pads-set-of-4-high-quality-isolation-pad...
#2: https://www.audiogon.com/stores/bba
The above butcher blocks come with "4 Free Anti-Vibration Pads With Every Platform".
As an example #1: https://www.audiogon.com/listings/lis997ac-sq-products-isol-pads-set-of-4-high-quality-isolation-pad...
#2: https://www.audiogon.com/stores/bba
The above butcher blocks come with "4 Free Anti-Vibration Pads With Every Platform".